| The records of dust concentration and size variations from several ice cores from low-latitude, high-altitude ice fields in South America and Asia are presented. At least three of these cores, Huascarán and Sajama from the Andes of South America, and Guliya from the Tibetan Plateau, contain information on tropical paleoclimate variations that extend back to (and in the case of Guliya, far beyond) the Late Glacial Stage. These records are examined here on time scale resolutions that vary from seasonal to centennial, and are compared with modern meteorological data and other published paleoclimate records.; The Huascarán and Sajama ice cores come from sites that lie in regions that have experienced opposite climates since the Last Glacial Maximum, when the Northern Andes were drier than the Bolivian Altiplano. There is evidence that Huascarán at 9°S may receive most of its fine-grained eolian dust during the wet austral summer from the arid and semi-arid regions of Africa. However, the most important season for dust deposition on Sajama at 18°S, much of which is from the Altiplano itself, is the dry austral winter.; The ice fields on the Tibetan Plateau receive most of their mineral aerosols in the late winter and early spring. The snowfall on Dasuopu in the Himalayas and Dunde on the northeast side of the Plateau is mainly monsoon-derived, while the snowfall for Guliya on the west side is from both the Indian monsoon in the summer and the prevailing westerlies in the winter.; Modern variations in the dust parameters from the Andean and Tibetan ice cores are associated with variations in sea level pressure dipoles in the subtropical and high-latitude North Atlantic, the tropical Pacific, and the circum-Antarctic Trough. The long ice core records show LGM to Early Holocene climate changes that broadly agree with the regional and global patterns of climatic transition, e.g. the strengthening of the Asian Monsoon into the Early Holocene and the retreat of the Northern Hemisphere ice sheets. These dust data should be useful for refining climate models that try to reconstruct past global aridity and predict future effective moisture. |
